A common construction of compressed air guns, including both pistols and rifles, involves an operating lever which is moved from an open to a closed position by the marksman prior to firing. In so doing, the marksman compresses a quantity of air which subsequently is used to propel the projectile. Typically, the operating lever is pivoted with respect to the weapon, such that in the open position it is disposed laterally away from the gun with its free end, and in the closed or locked position it rests against the gun, generally parallel to the barrel of the weapon. During movement of the lever from the open position to the locked position it moves the part which compresses the air. Thus, to prepare to fire the marksman moves the pivoted operating lever from its open position towards him to the closed position.
Motion of the operating lever from the closed to the open position is opposed only by small suction forces, such that the lever moves freely. On the other hand, in order to close the lever, the marksman must exert substantial force on the handle of the lever in order to compress the gas later used to propel the projectile.
A difficulty which is engendered by this design is that should the marksman release the lever before the lever has reached its closed position in which it is retained by a catch, an overcenter linkage or similar mechanism, the lever rapidly pivots, essentially unimpeded, due to the substantial force exerted by the compressed gas. Thus the lever can move to its open position rather violently and since its free end is pointed laterally towards the rear of the weapon the lever may strike the marksman and cause him injury. This is especially true when the marksman operates the lever of the weapon to compress air when the marksman is in the prone firing position, in which typically the operating lever is disposed very close to the marksman's face.